This invention relates generally to electrical wiring devices and more particularly to a wiring device having a one piece mounting strap and ground plate for reducing the number of parts needed to make the wiring device, and tracing the reliability and convenience thereof.
Electrical wiring devices of the type with which this invention is concerned include a ground plate, usually including a screw or other fastener for attaching a ground wire to the wiring device. Two types of ground plate are commonly used in known wiring devices. A first type of ground plate is integrally formed with a mounting strap portion of the wiring device, that is the plate or strap that is used to mount the device in an electrical junction box.
The mounting plate or strap is typically a stamped metal part, carrying the body of the wiring device in a center portion thereof and having axially extending mounting ears or plates through which mounting screws pass to attach the wiring device to a junction box. In accordance with one known technique for forming a grounding plate, a lateral plate is formed in the mounting plate when it is stamped out, and the plate is bent in a direction transverse to the long (axial) dimension of the mounting plate, and a mounting screw is fitted to the bent plate for attaching a ground lead. This technique is simple, inexpensive, and produces a good electrical connection because the ground plate is integrally formed with the mounting strap. However, this arrangement produces a ground screw that is oriented transversely to the axis of the wiring device, which is undesirable because it makes installation of the wiring device more difficult.
Another known wiring device arranges the ground plate so that the ground screw is oriented along the axis of the wiring device. This is preferred by installers, because installation is simplified, but heretofore all such arrangements have used a ground plate that is a physically separate element from the mounting strap, and which therefore must be physically and electrically attached to the mounting strap to form a low resistance connection that is also mechanically strong.
Providing a separate ground plate and attaching the ground plate to the mounting strap increases the cost of the wiring device, and can decrease the reliability thereof because of the need for making a mechanical and electrical attachment between the ground plate and the strap.
It is an object of this invention to overcome the disadvantages of both known constructions by providing a wiring device having a grounding plate that is integrally formed with the mounting strap and which includes a screw that is oriented along the axis of the wiring device.
It is another object of this invention to reduce the number of parts needed to form a wiring device having a grounding plate and screw oriented as described.